With the progress in computer network technology in recent years, the needs of utilizing World Wide Web (WWW) for businesses, transactions, work, and so on, have increased. Businesses are rarely carried out by individuals alone but, in general, a plurality of users simultaneously shares the same information, and carry out work in collaboration.
As a technology for providing the environment of collaboration work using Web, for example, there is a technology described in Japanese Patent Laid-Open Hei 10 (1998)-134461. This publication discloses a computer system and a method of execution invented for the purpose of providing a system designed to enable two or more users of the Internet to move or modify Hyper Text Markup Language (HTML) documents while referring to the same. The computer system described therein includes browsers and web sharing managers provided in the shared client computer systems of a source and a receiver, and is constructed in such a manner that the web sharing manager of the shared client computer system of the receiver can receive the event message of the source from the web sharing manager of the source. Accordingly, the event message is shared by the source and receiver, and the displaying and controlling of the same web page are simultaneously realized on the shared client computer systems.
In Japanese Patent Laid-Open Hei 5 (1993)-113975, a shared document processing system is described, which was invented for the purpose of displaying the modified place and content of a document shared and used by a plurality of users or groups of users, with comments. Specifically, the publication discloses a technology for storing a stored edited document, comments, edition information, and so on, in linkage, and retrieving these bits of information from terminals. In this case, for a plurality of terminals having an editor unit for editing each of the document comments, the edition information, and so on, or a management unit for each of those, a storage unit is provided in common to store each of the edited documents, the comments, the edition information, and so on. This arrangement enables a user to see the modified place and content of the document, a reason for the modification, and so on, while verifying the relation thereof Thus, it is considered that understanding of each other and the efficiency of collaborative editing work can be enhanced in sharing information within a work group.
In Japanese Patent Laid-Open Hei 10 (1998)-134002, a collaboration work support system is described, which was invented to enable a creator of drawing information or the like within a file, to be contacted by using optional communication means. According to this collaboration work support system, the contact address of a creator for the communication medium of at least one kind is stored corresponding to identification information regarding the creator of drawing information, the contact address information is obtained in response to an instruction from a user reading the drawing information, and the computer of the user is connected to the contact address of the creator.
The technologies described in the foregoing publications provides a collaboration work environment using WWW, makes it possible to refer to editing, comments and edition information regarding the document in common, and establishes user's quick contact with the creator of drawing information regarding the document or the like.
However, in the case of collaboration work carried out based on the conventional technologies, there is no concept of ownership for each object on a collaboration work area, i.e., no definition of who owns the object (ones of all the objects provided in the work environment, e.g., drawings, documents, characters, images, moving images, voices, combination of them and so on). Consequently, if a plurality of users take part in collaboration work, it is impossible to determine who owns a displayed object currently being drawn or who has drawn a currently displayed object that has already been drawn. In addition, there may be a case of selecting objects belonging to a certain owner, among the drawn objects, for editing operation including changing, modification, deletion, and so on. In the conventional technologies having no concept of ownership, however, such operations cannot be executed in the block.